29 June, 2009

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Alan Turing

Alan TuringThis obituary for Alan Turing appeared in The Times on June 16, 1954. The text refers to the war interrupting Turing’s mathematical career for six critical years. At the time that this article was written, Turing’s immense contribution to the cracking of the German Enigma code was a state secret of the highest order, and was to remain so for several more decades. There is also no mention in the text of Turing having committed suicide, a taboo subject in 1954.

ALAN TURING
Dr. Alan Mathison Turing, O.B.E., F.R.S., whose death at the age of 41 has already been reported, was born on June 23, 1912, the son of Julius Mathison Turing.
He was educated at Sherborne School and at King’s College, Cambridge, of which he was elected a Fellow in 1935. He was appointed O.B.E. in 1941 for wartime services in the Foreign Office and was elected F.R.S. in 1951. Until 1939 he was a pure mathematician and logician, but after the war most of his work was connected with the design and use of automatic computing machines, first at the National Physical Laboratory and then since 1948 at Manchester University, where he was a Reader at the time of his death.
The discovery which will give Turing a permanent place in mathematical logic was made not long after he had graduated. This was his proof that (contrary to the then prevailing view of Hilbert and his school at Göttingen) there are classes of mathematical problems which cannot be solved by any fixed and definite process. The crucial step in his proof was to clarify the notion of a “definite process,” which he interpreted as “something that could be done by an automatic machine.” Although other proofs of insolubility were published at about the same time by other authors, the “Turing machine” has remained the most vivid, and in many ways the most convincing, interpretation of these essentially equivalent theories. The description that he then gave of a “universal” computing machine was entirely theoretical in purpose, but Turing’s strong interest in all kinds of practical experiment made him even then interested in the possibility of actually constructing a machine on these lines.
It was natural at the end of the war for him to accept an invitation to work at the National Physical Laboratory on the development of the ACE, the first large computer to be begun in this country. He threw himself into the work with enthusiasm, thoroughly enjoying the rapid alternation of abstract questions of design with problems arising out of the use of the machine. It was at this time that he became involved in discussions on the contrasts and similarities between machines and brains. Turing’s view, expressed with great force and wit, was that it was for those who saw an unbridgeable gap between the two to say just where the difference lay.
The war interrupted Turing’s mathematical career for the six critical years between the age of 27 and 33. A mathematical theory of the chemical basis of organic growth which he had lately started to develop has been tragically interrupted, and must remain a fragment. Important though his contributions to logic have been few who have known him personally can doubt that, with his deep insight into the principles of mathematics and of natural science, and his brilliant originality, he would, but for these accidents, have made much greater discoveries.
Source: The Times [http://www.the-times.co.uk/]




23 June, 2009

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Waktu

jam matahari Matahari adalah penunjuk waktu pertama bagi manusia. Dahulu sekali orang memperkirakan waktu dengan cara memperhatikan posisi Matahari di Langit. Kemudian manusia memperhatikan bahwa bayangan mereka berubah-ubah panjangnya dan terus bergerak sepanjang hari.
Mereka menemukan bahwa dapat menentukan waktu secara lebih akurat dengan memperhatikan bayangan-bayangan mereka ketimbang dengan cara melihat posisi Matahari secara langsung. dari pengalaman tersebut kemudian manusia membuat jam matahari pertamanya. Pada awalnya, mungkin,manusia hanya menancapkan sebuah tongkat ke tanah, dan menempatkan beberapa batu di sekitar tongkat tersebut untuk menandai letak-letak dari bayangan-bayangan yang muncul. Jam-jam matahari ini telah digunakan selama berabad-abad dan masih tetap digunakan sampai sekarang.



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Jam Matahari

Manusia selalu mengelola kehidupannya sejalan berputarnya waktu. Para pemburu zaman harus berburu selama hari masih siang. ketika pola pertanian mulai dikembangkan, maka hal yang penting bagi para petani untuk mengetahui musim apa yang sedang mereka alami agar tanaman yang biasa mereka panen dapat ditanam pada waktu yang tepat.
Dahulu sekali, manusia menyadari bahwa pergerakan Matahari memungkinkan mereka untuk mengetahui peredaran waktu setiap harinya.
Mereka juga menyadari bahwa Bulan mengitari Bumi secara teratur dan kenyataan ini dapat digunakan untuk menentukan secara kasar satuan waktu untuk satu bulan. kehidupan modern seperti sekarang ini tak akan terlepas dari masalah waktu,sehingga kita sebagai bagian dari kehidupan itu sendiri memerlukan penunjuk waktu yang bener-benar akurat dalam mengukur setiap detik dalam perputaran roda waktu.


17 June, 2009

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Etnis Malagasi Keturunan Bugis ?


ANTANANARIVO, Walaupun negara kecil, posisi geo-politik Madagaskar cukup vital di mata dunia internasional. Letaknya yang berada di lintasan perniagaan laut dunia, memang sangat strategis. Sejak abad 10, para pengembara Arab sudah merambah kawasan itu. Bahkan kisah "Sinbad The Sailor" yang terkenal sebagai bagian kisah "Seribu Satu Malam", diperkirakan berlatar-belakang pulau Madagaskar.

Para antropolog memperkirakan, etnis Malagasi, penduduk asli dan mayoritas di Madagaskar, memiliki hubungan keturunan dengan suku bangsa dari suatu tempat di Indonesia. Kemungkinan suku Bugis atau Bajo, yang sejak dulu piawai mengarungi lautan dan melakukan perdagangan antarbenua.

Namun jejak genetikanya belum tertelusuri secara meyakinkan, karena cepatnya arus migrasi dan perbauran penduduk di pulau tersebut. Para imigran itu membentuk kelompok dan kelas masyarakat baru di Madagaskar, yang mendapat kemerdekaan dari Prancis tahun1960.


Devisa utama Madagaskar bersumber dari pertanian. Terutama padi, singkong, vanili, cengkeh, dll. Hasil tambang grafit merupakan terbesar di dunia. Pada tahun1980, ditemukan sumber minyak bumi dan mineral lain berupa bauksit, emas, dan batu mulia. Belum dieksploitasi besar-besaran, namun sudah menjadi incaran para investor.

Mungkinkah pertarungan ambisi dua tokoh Madagaskar – Presiden Marc Ravalomanana, dengan Wali Kota Antananarivo, Andry Rajoelina – didasari oleh kemungkinan-kemungkinan pemanfaatan harta terpendam itu? Dan para pemilik modal, calon investor ikut bermain di dalamnya? Sebab, mustahil Wali Kota Rajoeli mampu menjadi oposisi yang tiba-tiba sanggup mengerahkan massa untuk mengguncang Madagaskar, jika tidak ada yang mendorong secara finansial? Juga mustahil Presiden Ravalomanana mampu menggalang pertahanan serta memanfaatkan media jika tidak memiliki dana berlimpah?

Madagaskar, sebagaimana negara-negara Afrika lain yang kerap dilanda kemelut pemerintahan, sedang menunggu ujung penyelesaian. Negara "cengkeh" dan punya "hubungan darah" dengan Indonesia itu, sedang mencari penyelamatan nasib dari ujung tanduk. (Usro/A-147)***
 

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